1042SCG Genetics and Evolutionary Biology – Module 1 Lecture 1

These flashcards cover the major concepts introduced in Module 1 Lecture 1, including course structure, molecular biology fundamentals, differences between prokaryotic and eukaryotic cells, gene expression, the cell cycle, mitosis, binary fission, and chromosome terminology.

Which molecule serves as the ‘vehicle for inheritance’?

Nucleic acids (DNA and RNA).

State the Central Dogma of Molecular Biology.

DNA → RNA → Protein (via transcription and translation).

Define a gene.

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA.

Define a genome.

The complete set of DNA in a cell.

Define a chromosome in eukaryotes.

One of several DNA molecules packaged with proteins, found in the nucleus.

Where does transcription occur in a eukaryotic cell?

Inside the nucleus.

Where does translation occur?

On ribosomes in the cytoplasm or on the rough endoplasmic reticulum.

Which ribosomes synthesise proteins destined for secretion?

Ribosomes bound to the rough endoplasmic reticulum.

Is the nuclear membrane impermeable?

False – it contains nuclear pores that allow regulated transport.

List three features unique to prokaryotic cells.

DNA in a nucleoid (no nuclear membrane), lack of membrane-bound organelles, generally smaller size (<5 µm).

List three features unique to eukaryotic cells.

DNA enclosed in a nucleus, presence of membrane-bound organelles (ER, Golgi, mitochondria), larger cell size (10–100 µm).

Name two structures that can be present in both prokaryotic and eukaryotic cells.

Cell membrane and ribosomes (also cell wall and flagella in some cases).

What is binary fission?

The asexual cell division process used by prokaryotes to produce two genetically identical daughter cells.

Outline the three major steps of binary fission.

1) DNA replication from a single origin, 2) cell elongation with segregating chromosomes, 3) septum formation and cytokinesis producing two cells.

What are the two main types of eukaryotic cell division?

Mitosis and meiosis.

Why is meiosis necessary for sexual reproduction?

It reduces chromosome number by half and increases genetic variability of offspring.

Name the two overall phases of the eukaryotic cell cycle.

Interphase and the Mitotic (M) phase.

List the three sub-phases of interphase.

G1 phase, S phase, and G2 phase.

What key event occurs during the S phase?

Replication (duplication) of the cell’s DNA.

What is the primary activity in the G1 phase?

Normal cell functions such as protein synthesis, metabolism, and growth.

What happens during the G2 phase?

Further growth, DNA repair, and duplication of centrosomes.

Define a centrosome.

A region containing material that organises microtubules; in animal cells it includes a pair of centrioles and forms the spindle apparatus.

List the five classic stages of mitosis (abbreviation PPMAT).

Prophase, Prometaphase, Metaphase, Anaphase, and Telophase.

What characterises prophase?

Chromosomes condense, and the mitotic spindle begins to form.

What key event defines metaphase?

Duplicated chromosomes align at the metaphase plate.

How do sister chromatids separate during anaphase?

Spindle microtubules shorten, pulling sister chromatids toward opposite poles.

What marks telophase?

Chromosomes decondense and new nuclear envelopes reform around each set of chromosomes.

Describe cytokinesis in animal cells.

Actin microfilaments form a cleavage furrow that pinches the cell membrane, splitting the cytoplasm into two daughter cells.

What is a karyotype?

A photographic representation of the chromosomes in a cell, arranged by size and shape.

Define diploid (2n).

Having two sets of homologous chromosomes—one set inherited from each parent.

What is ploidy?

The number of complete sets of chromosomes in a cell (e.g., haploid n, diploid 2n, polyploid 3n/4n/etc.).

How many chromosomes do normal human somatic cells contain?

46 chromosomes (23 homologous pairs).

Why must organelles be duplicated before cell division?

To ensure each daughter cell receives the necessary components to function properly after division.